[PATCH v3] rtc: ds1307: generalise ram size and offset

[Austin Boyle]

Hi Wolfram,

Is the git tree you created for the ds1307 still active? How do you go about getting
those patches merged into linux-next?

Could you commit the following patch to your tree? Otherwise should I just create a
new patch against the latest kernel and send it to Andrew Morton?

Cheers,
Austin.

---

This patch generalises NVRAM to support RAM with other size and offset, such
as the 64 bytes of SRAM on the mcp7941x. Register offsets are added to chip
description instead of being hard-coded into probe function.

Signed-off-by: Austin Boyle <Austin.Boyle@xxxxxxxxxxxx>
---
this patch is based on Wolfram Sang's tree:
git://git.pengutronix.de/git/wsa/linux-2.6.git ds1307

patch depends on:
rtc: ds1307: comment and format cleanup 21af5f7bd6
rtc: ds1307: simplify irq setup code  8c63e03627
rtc: ds1307: refactor chip_desc table e246db081d
rtc: add initial support for mcp7941x parts e69bba2d3a

--- a/drivers/rtc/rtc-ds1307.c	2011-10-10 11:22:22.674690998 +1300
+++ b/drivers/rtc/rtc-ds1307.c	2011-11-04 10:02:27.859155009 +1300
@@ -104,6 +104,8 @@ enum ds_type {
 
 struct ds1307 {
 	u8			offset; /* register's offset */
+	u16			nvram_offset;
+	u16			nvram_size;
 	u8			regs[11];
 	enum ds_type		type;
 	unsigned long		flags;
@@ -119,26 +121,37 @@ struct ds1307 {
 };
 
 struct chip_desc {
-	unsigned		nvram56:1;
 	unsigned		alarm:1;
+	u8			offset;
+	u16			nvram_offset;
+	u16			nvram_size;
 };
 
 static const struct chip_desc chips[last_ds_type] = {
 	[ds_1307] = {
-		.nvram56	= 1,
+		.nvram_offset	= 8,
+		.nvram_size	= 56, /* 56 bytes NVRAM */
 	},
 	[ds_1337] = {
 		.alarm		= 1,
 	},
 	[ds_1338] = {
-		.nvram56	= 1,
+		.nvram_offset	= 8,
+		.nvram_size	= 56, /* 56 bytes NVRAM */
 	},
 	[ds_1339] = {
 		.alarm		= 1,
 	},
+	[ds_1388] = {
+		.offset		= 1, /* seconds starts at 1 */
+	},
 	[ds_3231] = {
 		.alarm		= 1,
 	},
+	[mcp7941x] = {
+		.nvram_offset	= 0x20,
+		.nvram_size	= 64, /* 64 bytes SRAM */
+	},
 };
 
 static const struct i2c_device_id ds1307_id[] = {
@@ -543,8 +556,6 @@ static const struct rtc_class_ops ds13xx
 
 /*----------------------------------------------------------------------*/
 
-#define NVRAM_SIZE	56
-
 static ssize_t
 ds1307_nvram_read(struct file *filp, struct kobject *kobj,
 		struct bin_attribute *attr,
@@ -557,14 +568,15 @@ ds1307_nvram_read(struct file *filp, str
 	client = kobj_to_i2c_client(kobj);
 	ds1307 = i2c_get_clientdata(client);
 
-	if (unlikely(off >= NVRAM_SIZE))
+	if (unlikely(off >= ds1307->nvram_size))
 		return 0;
-	if ((off + count) > NVRAM_SIZE)
-		count = NVRAM_SIZE - off;
+	if ((off + count) > ds1307->nvram_size)
+		count = ds1307->nvram_size - off;
 	if (unlikely(!count))
 		return count;
 
-	result = ds1307->read_block_data(client, 8 + off, count, buf);
+	result = ds1307->read_block_data(client, ds1307->nvram_offset + off,
+								count, buf);
 	if (result < 0)
 		dev_err(&client->dev, "%s error %d\n", "nvram read", result);
 	return result;
@@ -582,14 +594,15 @@ ds1307_nvram_write(struct file *filp, st
 	client = kobj_to_i2c_client(kobj);
 	ds1307 = i2c_get_clientdata(client);
 
-	if (unlikely(off >= NVRAM_SIZE))
+	if (unlikely(off >= ds1307->nvram_size))
 		return -EFBIG;
-	if ((off + count) > NVRAM_SIZE)
-		count = NVRAM_SIZE - off;
+	if ((off + count) > ds1307->nvram_size)
+		count = ds1307->nvram_size - off;
 	if (unlikely(!count))
 		return count;
 
-	result = ds1307->write_block_data(client, 8 + off, count, buf);
+	result = ds1307->write_block_data(client, ds1307->nvram_offset + off,
+								count, buf);
 	if (result < 0) {
 		dev_err(&client->dev, "%s error %d\n", "nvram write", result);
 		return result;
@@ -605,7 +618,6 @@ static struct bin_attribute nvram = {
 
 	.read	= ds1307_nvram_read,
 	.write	= ds1307_nvram_write,
-	.size	= NVRAM_SIZE,
 };
 
 /*----------------------------------------------------------------------*/
@@ -638,7 +650,19 @@ static int __devinit ds1307_probe(struct
 
 	ds1307->client	= client;
 	ds1307->type	= id->driver_data;
-	ds1307->offset	= 0;
+
+	if (chip && chip->offset)
+		ds1307->offset = chip->offset;
+	else
+		ds1307->offset = 0;
+	if (chip && chip->nvram_size)
+		ds1307->nvram_size = chip->nvram_size;
+	else
+		ds1307->nvram_size = 0;
+	if (chip && chip->nvram_offset)
+		ds1307->nvram_offset = chip->nvram_offset;
+	else
+		ds1307->nvram_offset = 0;
 
 	buf = ds1307->regs;
 	if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
@@ -756,9 +780,6 @@ static int __devinit ds1307_probe(struct
 						  hour);
 		}
 		break;
-	case ds_1388:
-		ds1307->offset = 1; /* Seconds starts at 1 */
-		break;
 	default:
 		break;
 	}
@@ -893,11 +914,12 @@ read_rtc:
 		dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
 	}
 
-	if (chip && chip->nvram56) {
+	if (chip && chip->nvram_size) {
+		nvram.size = ds1307->nvram_size;
 		err = sysfs_create_bin_file(&client->dev.kobj, &nvram);
 		if (err == 0) {
 			set_bit(HAS_NVRAM, &ds1307->flags);
-			dev_info(&client->dev, "56 bytes nvram\n");
+			dev_info(&client->dev, "%zd bytes nvram\n", nvram.size);
 		}
 	}
 



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